1. Field of the Invention
The present invention relates to a method for producing a clay/AMO complex and, more particularly, to a method for producing a silicate clay/AMO complex in which the AMO (amine-terminated Mannich oligomer) is prepared from the Mannich reaction of p-cresol and serves as an intercalating agent. The present invention also relates to a method for producing nanosilic plates from the clay/AMO complex.
2. Related Prior Art
Currently, inorganic/organic polymer complex materials under a nanoscale regime are one of the most significant materials, and thus have been widely investigated and developed. Such complex materials are dual-phased wherein at least one phase is dispersed under a nanoscale regime. Accordingly, compatibility between the two phases, for example, clay and polymers, is always essential for the nanoscale dispersion.
For layered silicate clay which is hydrophilic and immiscible with most organic solvents, the interlayer distances can be enlarged by means of intercalating with organic quaternary ammonium, and thus monomers are allowed to enter therethrough. The monomers can be polymerized within the interlayer space to obtain an exfoliated inorganic/organic polymer complex material. In principle, the distances, enlarged by intercalating agents, are constant and required to be wide enough for monomer or polymer molecules to enter. As for exfoliation, the interlayer distances are irregular and different directions may occur in each layer.
Conventional intercalating agents such as 12-aminolauric acid, hexadecylamine, fatty amine, bis(2-hydroxyethyl)methyl tallow alkyl amine and stearylamine, usually have low molecular weights and can be converted into the corresponding ammonium salts such as quaternary chloride salt, and interlayer distances of the clay can be ionically exchanged and hence sterically expanded to a certain degree of interlayer spacing.
Referring to the research of T. J. Pinnavaia (Michigan State University), intercalating agent CH3(CH2)n—NH3+ is provided to exchanged with metal ion salts within the layer-structural montmorillonite (MMT) in resulting intercalated MMT, which is then dispersed in diglycidyl ether of BPA (such as epoxy resin Shell Epon828) to form a epoxy polymer-clay complex material under a well-dispersed nanoscale regime. For such intercalating agent, the interlayer distances can be enlarged to 18.0 Å. The epoxy resin can then form an epoxy/clay material through curing polymerization at 75° C. This reference also indicates an improvement in heat distortion temperature. The intercalating agent performs a rule of monolayer to bilayer, and even to pseudo-trimolayer. The interlayer distance ranges between 13.8-18.0 Å, which allow the epoxy resin to enter and polymerize therein, and further to exfoliate the layered inorganic matter so that application advantages of nonomaterials can be achieved.
Japanese Patent No. 8-22946 discloses the first commercial inorganic/organic polymer complex material under a nanoscale regime, which is developed by Toyota Company. This complex material is produced by dispersing [H3N+(CH2)11COO−]-montmorillonite in Nylon 6, wherein the aminocarboxylic acid is provided as an intercalating agent and the polymers are formed between layers of the amino acid intercalated clay through condensation of caprolactam monomers to Nylon 6 polymer. However, the aminocarboxylic acid intercalating agent is hydrophilic and doesn't facilitate nonpolar polymers such as polyethylene and polypropylene, to uniformly disperse in the hydrophilic layered silicate. Accordingly, Japanese Patent Publication No. 8-53572 provides other organic onium ions as an intercalating agent to mix with layered silicate, which can be uniformly dispersed in molten polyolefin resin. Unfortunately, though the organic onium ions can enlarge the interlayer distances to certain degree, affinity between the intercalating agent and the polyolefin resin is not enough to exfoliate the layered silicate. Further, Japanese Patent Publication No. 10-182892 indicates that when blending in a molten mixture containing olefin oligomers with H-bond and polyolefin resin, the organized layered silicate might be indefinitely swelled due to the strong affinity therebetween. However, it's a dilemma whether to increase the oligomers for better dispersing or to decrease the oligomers for better mechanical characteristics.
Accordingly, there is a need to ameliorate the complexes by means of providing appropriate intercalating agents which could render the intercalated silicates with a wider interlayer distance and tailored spacing for more compatible with polymer materials. Furthermore, the widely opened silicates can be further tailored and used as novel inorganic/organic surfactants, an important industrial application but deviated from the common nanocomposite usages.